Mercury switch



June 19, 1928. 1,674,601

. l. E. MOCABE ET AL MERCURY SWITCH Filed Oct. 22, 1924 171067710715": /1f 7% M #1 I 2. 47% CW Patented June 19, 1928.

UNITED STATES.

PATENT OFFICE.

IBA. E. MCCABE AND RAYMOND W. ARMSTRONG, OF CHICAGO, ILIEIINOIS; SAID ARM- STRONG ASSIGNO R TO THE ARCLESS CONTACT COMPANY, A CORPORATION 01 rumors.

Application filed October 22, 1924. Serial No. 745,134.

Mercury switches in which contact is intended to be made and broken between mercury and 'a solid terminal have been developed to a degree that insures them extremely long life without deterioration. For some purposes it is desirable that the-circuits be made and broken between two bodies of mercury, the usual construction involving the use of a small well in the bottom of the switch tube or casing, the well being intended always to remain full of mercury. In this latter type of switch the current has usually been carried to and from the switch through asmall leading-in wire projecting into the well through the bottom thereof;

a this construction being admirable under or- 4 air to enter.

dinary conditions. However, it not infrequently happens that the mercury flows out of the well when the switch is tilted beyond a predetermined an'gle and, if current is then flowing, the break occurs and the arc is formed between the small leading-in wireand the mercury. When arcing occurs be! tween a small leading-in wire and the mercury, the leading-in wire is burned away wholly or in part, breaking the seal -between the wire-and the wall of the tube or receptacle into which the wire extends, allowing Therefore, even though the switch may continue to operate thereafter, the mercury will be sluggish through oxidation. I

The object of the present invention is to produce a switch of the type in which contact is made and broken between two bodies of mercury, which shall be free from the objections. heretofore noted and which shall continue to function in an unimpaired condit-ion even though the interruption of the circuit at times occurs between. mercury and I a solid terminal.

- We accomplish this object by making each terminal of a switch a double terminal which;

sealed glass tube MERCURY SWITCH.

bodies or casings of the best types of mcrcury switches are made of glass and are hermetically sealed. The leading-in wires -must therefore be sealed through the glass;

It is comparatively easy to make a perfect seal around a small wire but, as the size of the wire increases,-difiiculty (is experifor its object to produce a simple and novel'-- 'mercury switch having large leading-in wire,

capacity, without beingopen to the objection that it is difiicult to form a seal between the wires and the glass.

In carrying out this latter feature of our lnvention, we substitute for each single leading-in wire a. plurality of wires passing through the glass at points remote from each other so that each may be sealed without'aifecting the seal of the other wire or wires; the inner ends of what may be termed each multiple leading-in wire being so located relatively to each other as to constitute,in effect, a single terminal. 7

The various features of novelty whereby our invention is characterized will hereinafter be pointed out with particularity in the claims; but, for a full understanding of our invention and of its objects and advantages, reference may be had to the following detailed description taken in connection with the accompanying drawing, wherein: Figure 1 is a side view of a mercury switch embodying the present invention in a simple form; Fig. 2 is a longitudinal vertical section through the switch shown in Fig. 1; Fig. 3 is a view similar to Fig. 2, showing a modification; and Fig. 4 is a view similar to Figs. 2 and 3, illustrating not only a simple form of the invention but also the form containing multiple leading-in wires.

Referring to Fi s. 1 and 2, 1 represents a aving in the bottom, at points remote from each other, two small wells, 2 and 3. Leading-in wires 4 and 5 pass through the upper side of the tube, one

directly above each well. On the inner end of each leading-in wire is an enlarged head a or terminal, these being indicated at 6 and 7 these heads or terminals being made of pure iron or other metal suitable for this purpose. The heads are spaced apart from the wall through which they pass by means 'of sleeves of glass 8 surrounding the inner vided into two bodies 9 and 10, the former I filling the well 2 and extending part way to the well 3. while the other simply fills the well 3. The head or terminal 6 is immersed in the larger of the two bodies, while wells is omitted. Referring to this 11 represents the tube and 12 a well 0 ning the head or terminal 7 projects into the smaller body of mercury in the well 3. This is the condition that exists at the time the circuit is broken so that, as will be seen, the

.arcing'that takes place is between the two bodies of mercury. If however, the right hand end of the tube had been swung down-v wardly far enough to permit the mercury to flow out of the well 3 before any break had occurred in the mercury to separate it into two bodies, the circuit would eventually the head or terminal 7. However, the terminal 7, having a construction similar to that of a terminal in a mercury switch wherein the making and breaking of the circuit is always between mercury and the solid terminal, and beingspaced apart from the glass wall of the tube,.no damage can result to .the terminals or to the seal, or to the glass from the abnormal use of the switch.

After repeated 0 eration of the switch'the solid memberof t e terminal at which the circuit is broken becomes coated with a film of mercury, sothat the mercury in the corresponding well climbs up somewhat on this -member when the switch is tilted to open position, causing the arc 'to be made at a Egint more remote from the glass than would the case if, thesolid terminal member were not present, and protecting the glass from the arc.

In the switch shown. in Fig. 3,- one of the out of the bottom thereof at or near t e end. 13 and 14 are leading-in wires entering the "tube through the upperfside of the tube. 15 and 16 are enlarged. heads or terminals on the inner ends of the leading-in wires projecting slightly into thewell 17 and terminating immediatel below the brim thereof.

The mercury is in icated as divided into two.

bodies 17 and 18, the former being a'small body fillin the well; this'bcing1 position. t is immaterial whet er or not figure,

the. open The switch shown in Fig. 4 isa combination of the switgh shown in Figs. 1 and 2 and another simple modification, In other words, it is the switch of Figs. 1 and 2 having additional leading-in wires orterminals entering the wells through the bottom. The Y tube is indicated at 21 and the wells at 22 and 23. Terminals 24 and 25 similar to the terminals 6 and 7 in Fig. 2 are secured to leading-in wires 27 and 28 extending through the top of the tube above the wells and project slightly into the wells, terminating immediately below the brim thereof. Other terminals, 29 and 30, are located in the wells and secured to leading-in wires 31 and 32 passing upwardly through the bottoms o the wells. The terminals are spaced apart from the glass bottoms of the wells by glass sleeves 33. The mercury is shown as divided into two have been broken between the mercury and bodies 9 and was in Fig. 2, the switch be-.

ing shown open. It will be seen that. the.

terminals 24 and 29 are immersed in the larger body of mercury, while the terminals 25 and 30 may contact with the smaller body of mercury in the. well 23. The break in the circuit has,therefore taken place between mercury and mercury. In the event of the tipping'of the switch far enough in either direction to empty either well, while current is flowing, the break will occur between the corresponding air of heads or terminals and mercury, no amage resulting.

The leading-in wires of each pair of terminals are adapted to be connected together outside of the switch so that no one terminal wires need not be solarge as to make cult the sealin of the same in the glass. Furthermore, t e seals-are all remote from each other, so that the heating of the glass while making one of the seals does not afiect 1- the glass at any of the other seals. The

arrangement shown is one of the simpler forms illustrating the use of what may betermed a multiple leading-in wire, but it willof. course be understood that this idea may be extended and elaborated.

In all forms illustrated the ternim'als above the wells. enter a slight the mouth of each well and terminate immediately below the brim thereof whereby should the tipping of the switch be far enough to empty the well upon tippin% in the opposite direction the mercury-will 'rst fill the well and then engage the terminal and in the event that an air pocket be formed in the bottom of the well the mercury supported thereabove will en age the ter- 'm.nal and contact will be esta lished to the other terminal.

While we have illustrated and described with particularity only a few simple forms of our invention, we do not desire to be limited to the exact structural details thus illustrated and described but intend to cover --all forms and arrangement coming within the definitions of our invention constituting .the appended claims. I

' upper side of the casing above each well,

and a large head or terminal on each of said second wires projecting slightly into the mouths of the wells and terminating immediately below the brims thereof, whereby both heads or terminals at each well will be in contact with the mercury in the well when the latter is tull.

2. A mercury switch comprising a casin in the form of a sealed tube having a smal well opening out of one side of the tube, a bodyof mercury only partially filling the casing but in excess of the capacity of the well, a leading-in wire extending through the side of the tube opposite the well, a large head or terminal secured on the inner end of said leading-in wire and projecting slightly into the well and terminating immediately below the brim thereof, and a second terminal located in position to engage with the mercury when it is united in one body and remain in engagement with the main portion of the mercury when the casing is tilted so as to separate the main portion of mercury from that in the well.

In testimony whereof, we sign this specification..

RAYMOND W. ARMSTRONG. IRA E. MoCABE. 

